Abstract:

We demonstrate the existence of an unusual and useful high-brightness guided mode of a multimode
AlGaAs/GaAs heterostructure compound slab waveguide. This mode has a narrow near-field single
lobe confined to the low-index regions of the waveguide. This mode was selectively probed by
optically exciting quantum wells optimally placed in the waveguide. By pumping in a stripe
geometry, lasing is observed above a threshold of 80 kW/cm2 indicating efficient lasing in the
highest-order waveguide mode. The near-field emission pattern of the waveguide was imaged to
provide a direct measurement of the intensity profile of the higher-order mode.